production of veterinary vaccines are given in Chapter 1.1.8 Principles of veterinary vaccine production. The
guidelines given here and in Chapter 1.1.8 are intended to be general in nature and may be supplemented
by national and regional requirements. If virulent forms of NDV are used in the production of vaccines or in
challenge studies, the facility should meet the OIE requirements for Containment Group 4 pathogens as
described in Chapter 1.1.2.